1. Field of the Invention
The present invention relates to data communications, and more particularly, to a device for data communications between a Wireless Application Protocol (WAP) terminal and a WAP server, and a method thereof.
2. Description of the Related Art
In general, a WAP server is connected between an Internet server which provides various information and a WAP terminal capable of receiving the information provided from the Internet server, to convert different data formats and different protocols between the Internet server and the WAP terminal. Also, the WAP server can provide the WAP terminal with its own information.
FIG. 1 is a block diagram of a conventional data communications device between a WAP terminal and a WAP server.
The data communications device of FIG. 1 comprises a WAP terminal 10, an interworking function (IWF) unit 12, a public switched telephone network (PSTN) 13, an Internet service provider (ISP) 14 and a WAP server 16.
The IWF unit 12 performs routing functions between the WAP terminal 10 and the ISP 14. The ISP 14 is one of companies providing general communication service such as HITEL or UNITEL. The WAP server 16 provides the WAP terminal 10 with its own information and much information from an Internet server (not shown).
FIG. 2 shows a protocol stack of each block of the data communications device shown in FIG. 1.
A protocol stack of the WAP terminal 10 consists of a plurality of protocol layers including a Circuit Switch Data services protocol (CSD(IS-707)), a Peer-to-Peer Protocol (PPP), an Internet Protocol (IP), a Wireless Transaction Protocol (WTP) and User Data Program Protocol (UDP), a Wireless Session Protocol (WSP) and a Wireless Application Environment protocol (WAE). Also, the CSD(IS-707) includes an IS-95 protocol, a Radio Link Protocol (RLP), a PPP, an IP and a TCP. The protocol layers are well known to those skilled in the art, so explanation thereof will be omitted.
FIG. 4 is a diagram illustrating data flow in the data communications device shown in FIG. 1.
The operation of the data communications device of FIG. 1 will be described with reference to FIG. 4.
It is assumed that the WAP terminal 10 intends to receive Internet or electronic mail (E-mail) services. Here, the WAP terminal 10 is ready to receive a common call or data (Internet or E-mail) in a normal state. When a user of the WAP terminal 10 connects the WAP terminal 10 through the IWF unit 12 and the PSTN 13 to the ISP 14 using a telephone number for connection with the Internet, the ISP 14 connected to the WAP terminal 10 allows the user to receive the Internet or E-mail services. Also, when the user wants to stop receiving the Internet services, the ISP 14 disconnects the call from the WAP terminal 10, returning to the ready state.
In detail, the WAP terminal 10 sends an Origination Message requesting connection of its call to the IWF unit 12. The IWF unit 12 receives the Origination Message from the WAP terminal 10, and then sends an Origination Ack message acknowledging reception to the WAP terminal 10. The IWF unit 12 sends a Connect Request message for connection of a modem to the ISP 14. The ISP 14 receives the Connect Request message and sends a Connect <rate> message indicating the connection of the modem through the PSTN 13 and the IWF unit 12 to the WAP terminal 10. Under conditions that the WAP terminal 10 and the IWF unit 12 are connected to each other, the WAP terminal 10 sends WAP data (Internet or E-mail services request data) which the user wants to receive through the IWF 12 and the ISP 14, to the WAP server 16. After the WAP server 16 receives the WAP data, the WAP server 16 sends WAP server data which is retained in the WAP server itself, or data taken from an Internet server (not shown) through the ISP 14, the PSTN 13 and the IWP 12 to the WAP terminal 10.
The data communications device of FIG. 1, having the protocol stack as shown in FIG. 2, has the following problems.
First, because the CSD(IS-707) in the protocol stack of the WAP terminal 10 includes the IP/PPP as shown in FIG. 3, the protocol stack of the WAP terminal 10 has IP/PPP protocol layers in duplicate. As a result, there is much overhead during transmission of data, so that transmission efficiency becomes low. That is, the resources of the terminal are not efficiently used. Also, when a user intends to connect to the WAP server 16 or the Internet, connection with the ISP 14 is achieved through the PSTN 14. Thus, the connection rate becomes slow, and using the PSTN and the ISP 14 may be subject to charges by the telephone company or the ISP. Also, the transmission of data is inefficient because it requires multiple steps as shown in FIG. 4.